Whilst there have been many significant advances in the development of new batteries and power networks for transportation and communication devices, different types of batteries can present problems when used in particular environments. For example, batteries currently used for electric powered vehicles suffer from a number of problems. High demands are placed on these batteries in terms of the current drawn from, and recharged to, the battery at various stages during vehicle operation. For example, in electric vehicles a high rate of discharge is needed from the battery to enable acceleration, and a high rate of recharging of the battery is associated with regenerative braking. In the situation where lead-acid batteries are utilised, particularly in hybrid electric vehicles, the high rate of battery discharging and recharging can result in the formation of a layer of lead sulphate on the surface of the negative plate, and the generation of hydrogen and oxygen gas at the negative and positive plates. This largely arises as a result of high current demands on the battery. The partial state-of-charge conditions (PSoC) under which these batteries generally operate is 20-100% for electric vehicles, 40-60% for hybrid electric vehicles, and 70-90% for mild hybrid electric vehicles. This is a high rate partial state-of-charge (HRPSoC). Under simulated HRPSoC duty, such as hybrid and mild hybrid electric vehicle operations, the lead-acid batteries can fail prematurely mainly due to the progressive accumulation of lead sulphate on the surfaces of the negative plates. This occurs because the lead sulphate cannot be converted efficiently back to sponge lead during charging either from the regenerative braking or from the engine. Eventually, this layer of lead sulphate develops to such an extent that the effective surface area of the plate is reduced markedly, and the plate can no longer deliver the higher current demanded from the automobile. This significantly reduces the potential lifespan of the battery.
Portable and rechargeable energy storage devices, such as rechargeable electrochemical batteries and capacitors, are becoming increasingly essential for powering a range of modern transportation and communication devices. As mentioned above, in many devices the combination of instantaneous high power or high rate along with high energy is required. Hybrid electrodes and batteries have been developed that combine an electroactive capacitor with an electrochemical battery to meet the peak power requirements of pulsed power applications. Although this type of combined construction can significantly enhance battery performance, such as providing enhanced cycle life, there are still various problems with such hybrid devices that still limit their overall performance and cycle life.
There is consequently a need to provide alternative electrodes and electrical storage devices including improved lead-acid batteries, which have an improved lifespan and/or performance compared to current batteries.